1. Field of the Invention
This invention relates to a coin inspection method and device for inspecting the authenticity of coins, and more particularly, to a coin inspection method and device suitable for inspecting coins used in an automatic vending machine, game machine, or the like.
2. Description of the Related Art
In recent years, electronic coin inspection devices employing induction coils have been used commonly as coin inspection devices used in automatic vending machines, game machines, and the like.
Generally, a coin inspection device of this kind employs the gravitational fall of coins, and is constituted in such a manner that a plurality of groups of induction coils are disposed in a coin passage which guides coins inserted via a coin insertion slot, electromagnetic fields are created by exciting the plurality of induction coil groups by means of respectively different frequencies, and the authenticity of coins inserted via the coin insertion slot is inspected by means of the change in the electromagnetic fields caused by the passage of the coins through the electromagnetic fields.
The inspection of the coins by means of this coin inspection device is based on commonly known principles, whereby the authenticity of a coin is identified by detecting the quantities of electrical change (frequency change, voltage change, phase change) arising from the interaction between the electromagnetic field and the coil when the coin passes through the aforementioned electromagnetic field.
Conventionally, in a coin inspection device of this kind, the characteristics of the coins depend on frequency parameters, and therefore by using a plurality of frequencies, it is possible to achieve a technique for inspecting the material, outer diameter, thickness, and the like, of coins, as disclosed in U.S. Pat. No. 3,870,137.
Moreover, in recent years, coin inspection devices employing a technique for detecting the surface shape of a coin have been proposed, representative examples thereof being the devices disclosed in Japanese Patent Application Laid-open No. 11-167655 and Japanese Patent application Laid-open No. 11-175793.
Furthermore, the induction coils in a conventional coin inspection device employ a pot-shaped core or an E-shaped coil.
In recent years, with the process of internationalization, foreign coins have become readily available, and there have been an increasing number of cases where such coins are mistakenly inserted into an automatic vending machine, or the like, or where they are inserted thereinto illegally by people seeking to commit fraud, or the like.
Of these foreign coins, there are those which are similar to genuine valid coins, in terms of material, outer diameter, thickness, and the like. Alternatively, foreign coins which have been made to simulate genuine valid coins by modification, or the like, have become available in large number.
Of these foreign coins and the foreign coins which have been modified, there are those which, although having a different surface design (indentation pattern) or a different coin edge (flange) shape from the genuine coins, have approximately the same material properties, outer diameter and thickness as genuine coins, and hence in a conventional coin inspection device, such coins may be accepted mistakenly as genuine coins, in which case, the proprietor of the automatic vending machine, or the like, will suffer unlawful losses.
Therefore, a technique which detects the indentation pattern of the coin surface and the shape of the edge section (flange) thereof with a high degree of accuracy is desired.
FIG. 18 is a graph of the characteristics of an induction coil used in a conventional coin inspection device.
In a conventional coin inspection device, a device wherein a coil 182 is wound about a center leg section 181 of an E-shaped core 180, as illustrated in FIG. 18, is used.
Looking at the distribution of the electromagnetic field generated at the respective magnetic poles of the induction coils, as illustrated in FIG. 18, the magnetic poles in the central region display the greatest strength, whilst at the magnetic poles at either end, the electromagnetic field is reduced to a fraction thereof, and hence the electromagnetic field acting on the coins is a simple peak-shaped electromagnetic field.
If a simple peak-shaped electromagnetic field of this kind is used, it is not possible to concentrate the magnetic flux acting on the coins, and therefore the electromagnetic field acts over a wide area of the coin surface, detection is slow, and it has been difficult to detect detailed features of the shape of the coin surface.
Moreover, in order to detect detailed features of the shape of the coin surface, it has been attempted to adopt optical methods using image detecting elements (CCD) in a coin inspection device of this type, but dust or the like may adhere to the coins, impairing coin authenticity judgement, and furthermore the device becomes not only larger, but also more complicated, and as a result, the overall device becomes expensive.
Therefore, it is an object of the present invention to provide a coin inspection method and device whereby the shape of the edge section of a coin and the indentation pattern on the surface thereof can be inspected with a high degree of accuracy, by means of a simple single-group coil composition, which is moreover inexpensive. In order to achieve the aforementioned objects, the present invention provides a coin inspection method, comprising the steps of: forming detecting coils by providing a first detecting coil on one of two adjacent leg sections of a core having a plurality of leg sections and a second detecting coil on the other one of the leg section respectively; generating a double-peak shaped magnetic field by exciting the first and second detecting coils in such a manner that magnetic fluxes generated at magnetic poles formed by the leg sections repel each other; causing a coin under inspection to pass through the double-peak shaped magnetic field; and inspecting characteristics of the coin under inspection on the basis of changes in electrical properties of the detecting coils generated by the passage of the coin under inspection.
Here, the detecting coils allows the coin under inspection to pass through a direction coincide with a disposing direction of the first and second detecting coils of the core.
Furthermore, an inspection signal is created on the basis of changes in the electrical properties generated in the detecting coils, and features of edge portions of the coin under inspection are extracted on the basis of a signal waveform of the inspection signal when the waveform increases or declines.
Furthermore, an inspection signal is created on the basis of changes in electrical properties generated in the detecting coils, and features of a pattern of indentations on a surface of the coin under inspection are extracted on the basis of a signal in a maximum change region of the inspection signal.
Furthermore, the present invention provides a coin inspection method, comprising the steps of: disposing a first and second detecting coils, which are respectively provided with a first detecting coil on one of two adjacent leg sections of a core having a plurality of leg sections and a second detecting coil on the other one of the leg section, on either side of a coin passage along which a coin under inspection passes, the first and second detecting coils being connected serially in reverse phase in such a manner that a mutual inductance thereof is negative; generating a double-peak shaped magnetic field toward the coin passage from the first and second detecting coils; causing the coin under inspection to pass through the double-peak shaped magnetic field; and inspecting characteristics of the coin under inspection on the basis of changes in electrical properties of the detecting coils generated by the passage of the coin under inspection.
Furthermore, the present invention provides a coin inspection device for passing a coin under inspection through a magnetic field generated by detecting coils and determining authenticity of the coin under inspection on the basis of changes in electrical properties of the detecting coils, wherein the detecting coils comprise: a core having a plurality of leg sections;
a first detecting coil and a second detecting coil provided respectively at two adjacent leg sections of the core; and magnetic field generating means for generating a double-peak shaped magnetic field by exciting the first detecting coil and the second detecting coil in such a manner that magnetic fluxes generated at magnetic poles formed by the two leg sections repel with each other.
Here, the core is constituted such that a cross-sectional shape of the leg sections is a square shape, a circular shape, or an oval shape, and both ends thereof are arc-shaped.
Furthermore, the detecting coils are disposed in such a manner that a direction in which the first detecting coil and second detecting coil are disposed in the core coincides with a direction of passage of the coin under inspection.
Furthermore, the coin inspection device comprises an oscillating circuit containing the detecting coils as a resonance element.
Furthermore, the coin inspection device comprises inspection signal generating means for generating an inspection signal on the basis of changes in electrical properties generated in the detecting coils; and means for extracting features of edge portions of the coin under inspection on the basis of the inspection signal when it increases or declines.
Furthermore, the coin inspection device comprises inspection signal generating means for generating an inspection signal on the basis of changes in electrical properties generated in the detecting coils; and means for extracting features of a pattern of indentations on a surface of the coin under inspection on the basis of a signal in a maximum change region of the inspection signal.
Furthermore, the present invention provides a coin inspection device for passing a coin under inspection through a magnetic field generated by detecting coils and determining authenticity of the coin under inspection on the basis of changes in electrical properties of the detecting coils, wherein the detecting coils comprise: a first detecting coil disposed along a passage of the coin under inspection, and provided in a core having a plurality of leg sections which generates a first double-peak shape magnetic field toward the coin passage; and a second detecting coil disposed along the coin passage in such a manner as to oppose to the first detecting coil and provided on a core having a plurality of leg sections which generates a second double-peak shaped magnetic field toward the coin passage.
Here, the first and second detecting coils are disposed in such a manner that a disposing direction of the plurality of leg sections of the core coincides with a direction of passage of the coin under inspection
Furthermore, the first and second detecting coils are connected serially in reverse phase, in such a manner that a mutual inductance thereof is negative.
Furthermore, the present invention provides a coin inspection device for examining physical properties of a coin and inspecting authenticity of the coin, comprising: a coin insertion slot; a coin passage coupled to the coin insertion slot; a first detecting coil disposed along the coin passage and generating a first double-peak shaped magnetic field toward the coin passage; a second detecting coil disposed opposing the first detecting coil on the other side of the coin passage therefrom and generating a second double-peak shaped magnetic field toward the coin; an oscillating circuit comprising the first and second detecting coil as a resonance element; a detection circuit for detecting changes in electrical properties of the first and second detecting coils on the basis of an output of the oscillating circuit; storing means for storing reference values for acceptable coins; comparing means for comparing a detection output of the detection circuit with the reference values stored in the storing means; and determining means for determining authenticity of the coin inserted via the coin insertion slot, on the basis of a comparison output of the comparing means.
Here, the first and second detecting coils respectively comprise: a core having a plurality of leg sections; first and second detecting coils provided respectively on two adjacent leg sections of the core; and magnetic field generating means for generating a double-peak shaped magnetic field by exciting the first and second detecting coils in such a manner that magnetic fluxes generated by magnetic poles formed by the two leg sections repel with each other.
Furthermore, the first and second detecting coils are disposed in such a manner that a disposing direction of the plurality of leg sections of the core coincides with a direction of passage of the coin under inspection.
Furthermore, the first and second detecting coils are connected serially in reverse phase, in such a manner that a mutual inductance thereof is negative.
In this invention, by adopting the composition described above, the detecting coils are self-excited by means of the oscillating circuit, and hence the magnetic fluxes between the two adjacent magnetic poles of the detecting coils repel with each other, thereby generating a double-peak shaped magnetic field. This double-peak shaped magnetic field is concentrated into respective beam shapes, which have an electromagnetic inducting action on the edge portions (flanges) of the coin and the surface section of the coin.
Due to the electromagnetic induction generated when the coin edge portions (flanges) pass between the aforementioned two magnetic poles, an eddy current is generated in the vicinity of the coin edge portions (flanges), and this eddy current generates an opposing magnetic field which disturbs the original magnetic field generated by the detecting coils, and hence causes the electrical properties (impedance) of the detecting coils to change. This impedance change varies in accordance with the features of the shape of the coin edge portions (flanges).
On the other hand, due to the electromagnetic induction arising when the pattern on the surface of the coin passes between the aforementioned two magnetic poles, an eddy current is generated in the vicinity of the coin surface region, and similarly to the foregoing, this eddy current generates an opposing magnetic field which disturbs the original magnetic field generated by the detecting coils, and hence causes the impedance of the detecting coils to change. This impedance change varies in accordance with the features of the indentations in the pattern on the coin surface.
In this way, since it is possible to cause a double-peak shaped magnetic field concentrated into beam shapes to act on the coin edge portions (flanges) and narrow regions of the coin surface, it is possible to improve the resolution of detection, and hence coin inspection can be performed with a high level of accuracy. Moreover, it is possible to obtain a plurality of detection factors for a coin by means of a single group of detecting coils.
In this way, according to the present invention, detecting coils are formed by providing a first detecting coil on one of two adjacent leg sections of a core having a plurality of leg sections and a second detecting coil on the other one of the leg section respectively; a double-peak shaped magnetic field is generated by exciting the first and second detecting coils in such a manner that magnetic fluxes generated at magnetic poles formed by the leg sections repel each other; a coin under inspection is caused to pass through the double-peak shaped magnetic field; and characteristics of the coin under inspection are inspected on the basis of changes in electrical properties of the detecting coils generated by the passage of the coin under inspection. Consequently, the shape of the coin edge portions (flanges) and the indentation patterns in the coin surface can be detected by means of a simple group of coils, and hence it is possible to provide a compact and inexpensive coin inspection device having high performance, for inspecting the authenticity of a plurality of coins.